NTSerialTool.cs

Console.WriteLine("NTSerialTool by substanc3");
int targetBaud = 4800;

var ipEndPoint = new IPEndPoint(IPAddress.Loopback, 31337);

using TcpClient client = new();
await client.ConnectAsync(ipEndPoint);
await using NetworkStream vStream = client.GetStream();
Console.WriteLine("Connected to VirtualBox.");

var ipEndPoint2 = new IPEndPoint(IPAddress.Any, 31338);
TcpListener listener = new(ipEndPoint2);

listener.Start();

using TcpClient handler = await listener.AcceptTcpClientAsync();
await using NetworkStream mStream = handler.GetStream();
Console.WriteLine("Connected to MAME.");

Queue<byte> vQueue = new Queue<byte>();
Queue<byte> mQueue = new Queue<byte>();

var vBuffer = new byte[1];
var mBuffer = new byte[1];

var vTask = vStream.ReadAsync(vBuffer).AsTask();
var mTask = mStream.ReadAsync(vBuffer).AsTask();
var timeTask = Task.Delay(1000 / (targetBaud / 8));

while(true)
{
    var task = await Task.WhenAny(vTask, mTask, timeTask);
    if (task == vTask)
    {
        var amt = await vTask;
        for (int i = 0; i < amt; i++)
        {
            vQueue.Enqueue(vBuffer[i]);
            vBuffer[i] = 0;
        }

        vTask = vStream.ReadAsync(vBuffer).AsTask();
    }
    else if (task == mTask)
    {
        var amt = await mTask;
        for (int i = 0; i < amt; i++)
        {
            mQueue.Enqueue(mBuffer[i]);
            mBuffer[i] = 0;
        }

        mTask = mStream.ReadAsync(mBuffer).AsTask();
    }
    else if (task == timeTask)
    {
        if(vQueue.Count > 0)
        {
            var b = vQueue.Dequeue();
            await mStream.WriteAsync(new byte[] { b });
        }
        else if (mQueue.Count > 0)
        {
            var b = mQueue.Dequeue();
            await vStream.WriteAsync(new byte[] { b });
        }
        await timeTask;
        timeTask = Task.Delay(1000 / (targetBaud / 8));
    }
    else
        Console.WriteLine("Error");
}